The manner of lighting interior spaces has traditionally been dictated by the form of the illumination source, which in turn is constrained by the method of producing light. The evolution of lighting sources provides a static, fixture-based approach to lighting. This fixture-based approach to lighting suffers numerous shortcomings Light fixtures can typically be high intensity sources that cannot be viewed directly, and such lights can cast a harsh, non-uniform light throughout a room.
One newer type of lighting uses a uniform lighting material, such as an OLED sheet, to cast a more natural, diffused light into a room. However, implementing this approach can require rethinking of lighting design to account for potential interference with building architecture, furniture, and added decorations such as framed art, etc. For such lighting as OLED, the deployment of distributed lighting sources on non-traditional surfaces presents a challenge that can limit customer acceptance.
Another primary source of lighting that is prevalent in buildings are windows. Windows provide solid, weather-proof means for allowing natural light to enter and illuminate the interior of buildings. During the day, windows are the ideal source of room light, providing illumination far superior in brightness, uniformity and color quality to artificial light. However, existing windows typically can only provide sufficient light during the day when sufficient sunlight is available, and usually only to rooms adjacent to an exterior surface of a building.
It is conceivable to provide an artificial light source on the outside of a window so that a window may provide natural lighting during the day and artificial lighting when supplemental lighting is needed, such as at night or on cloudy days. Such an approach would allow for consistency and economy of lighting design, insofar as rooms are generally configured to accept light from windows, and therefore, no special design concessions would be required to accommodate extra light sources. However, this approach also has a disadvantage in that a light source would then need to be positioned outside, and a portion of the window would be obstructed by the artificial light source. Thus, there remains a need for improving interior lighting without requiring intrusive interior fixtures.